This invention relates to a method of fabricating an optical recording medium, and more particularly to a method of fabricating an optical recording medium that is adaptive for fabricating an optical recording medium adopting a frame wobbling system in which a same-phase wobbling area and a different-phase wobbling area coexists in a track. Also, the present invention is directed to an exposure apparatus that is adaptive for irradiating a light on a master disc for duplicating an optical recording medium adopting a frame wobbling system.
Recently, an optical recording medium, an magneto-optical recording medium and so on have been developed as a recording medium for recording various information, such as video and audio information, etc., and have been commercially available in the market. Such an optical recording medium includes a read-only type disc such as CD-ROM and DVD-ROM, etc., a write-once-read-many type disc such as CD-R and DVD-R, etc., and a rewritable type disc such as CD-RW, DVD-RAM, etc.
An identification information including an address information, etc. is recorded on a conventional rewritable disc in advance so that an information can be recorded at a desired position. In an optical disc such as CD-R, etc., land signal tracks 10 and groove signal tracks 12 are formed as shown in FIG. 1, and an identification (ID) information including an address information, etc. is recorded on each side of the groove signal track 12. Such an identification information is pre-formatted in a wobbled pattern on each side of the groove signal track 12 in accordance with a frequency-modulated carrier signal. An address information can be read out by an wobbling signal detected from the wobbled groove signal track 12, and an information can be recorded on a desired position of the disc on a basis of this address information. In such a disc, however, an information recording capacity is limited because an information is recorded only on the groove signal track 12.
A disc (e.g., DVD-RAM) as shown in FIG. 2 has been known as a disc in which an information can be recorded on all the land and groove signal tracks. This disc includes header fields having an identification information including an address information, etc. recorded in a form of pre-pit trains 14 and recording fields consisting of the land and groove signal tracks 10 and 12 wobbled in the same phase. Such a disc has a limited recording capacity because an information can not be recorded on the header field consisting of the pre-fit trains 14.
Meanwhile, an optical recording medium in which same-phase wobbling areas 24A and different-phase wobbling areas 24B each having a predetermined interval are alternated at the land and groove signal tracks 20 and 22, is disclosed in U.S. patent application No. 09/134,368 filed on Aug. 14, 1988 by the applicant. As it were, the optical recording medium is called frame wobbling recording medium. In the frame wobbling recording medium, an information can be recorded on all of the same-phase wobbling area 24A and the different-phase wobbling area 24B by an ID information on the same phase wobbling area 24. Since such a frame wobbling recording medium can record an information on all the land and groove signal tracks 20 and 22 and can record an information on all of the same-phase wobbling area 24A and the different-phase wobbling area 24B in accordance with an ID information on the same-phase wobbling area 24A without a separate ID information, it has an enlarged recording capacity. However, since frame wobbling recording medium has a track structure in which the same-phase wobbling area 24A is alternated with the different-phase wobbling area 24B, it is difficult to fabricate the frame wobbling recording medium using a method similar to the conventional optical recording medium fabricating method.
Accordingly, it is an object of the present invention to provide a method of fabricating an optical recording medium that is adaptive for fabricating a frame wobbling recording medium.
A further object of the present invention is to provide an exposure apparatus that is adaptive for irradiating a light on a master disc for duplicating a frame wobbling recording medium.
In order to achieve this and other objects of the invention, a method of fabricating an optical recording medium according to one aspect of the present invention includes the steps of providing a wobbling signal for pre-formatting an identification information for the corresponding area with respect to a first wobbling area; providing a wobbling signal for pre-formatting an identification information for the first wobbling area positioned at the adjacent tracks with respect to a second wobbling area; and irradiating a light in accordance with a signal in which the two wobbling signals are alternately combined.
An exposure apparatus for an optical recording medium according to another aspect of the present invention includes wobbling signal generating means for providing a wobbling signal for pre-formatting an identification information for the corresponding area with respect to a first wobbling area and for providing a wobbling signal for pre-formatting an identification information for the first wobbling area positioned at the adjacent tracks with respect to a second wobbling area; and irradiating means for irradiating a light onto a master disc for duplicating the optical recording medium in response to a signal in which the two wobbling signals are alternately combined.